Here is an old thread that shows where it is.

https://www.ford-trucks.com/forums/1...-location.html

 

Ok and this will solve the pressure, relays just send eletricity

 

It may fix it, IDK. If you changed your fuel pump, it's a good idea to replace the relay, too. Cheap part could extend the life of your new pump.

 

You should have added: "TO THE PUMP!!" in order to better understand this suggestion! After all if there's no electricity to the pump it ain't gonna run now is it??

Its my experience when/if the fuel pump is replaced its a good idea to change the relap and FPR at the same time. Logically this makes sense especially if there's enough miles or time on the system.

Yes fuel pumps tend to be go/no go items however as already said before they fail completely output begins to drop. The OP had 290K miles which is a good life span for most higher pressure fuel system components.

 

I have a 99 250 sd v10. Where is the fuel pump pressure regulator? My pressure is 38 with key on, 34 at idle. When I add rpm it goes up a bit then back down to 34.
SM

 

The Fuel Pressure Regulator is attached to the back of the intake manifold, and is between manifold and the firewall.

 

Ty Northwind. gonna check that tomorrow.
SM

 

I can't see or feel my FR. How do I check it?
SM

 

M v10 runs rough with 1/2 tank or less and gets worse as the tank level goes down. I am going to drive it today with the fuel pressure gauge attached.

With 1/2 tank cold in the driveway fuel pressure is at 30 to 40 psi.........
I am hoping it will get worse when warm so I can be sure of the fuel pump.

Could it have good pressure but bad volume?

 

do you have any better pics of it to give me an idea how to get it out I can feel it with my fingers and found the torcs bit that's needed

 

So I'm having the same kinda problem I have about 30psi at key on at an idle I have 22psi and at wot I have about 30psi when I pull the vacuum line off the pressure regulator at an idle the fuel pressure gos from 22psi to 30psi. Dose this mean my regulator is bad ? Or my pump ? Just bought the truck thinking maybe it gets worse when the tanks low but it could just be me. 99 F-250 SD V10 256,000km

 

The fuel pressure regulator is vacuum referenced.
With the key on engine off fuel pressure should be about 20 in hg (at sea level) or 10 psi ish higher than at idle. Depending on how much vacuum you are pulling, and your elevation.

I think you should see around 32 psi pressure at idle and 38 to 40 with no vacuum.

 

I'm seeing 22 psi at idle and around 32psi at wot.
But at the same time if I take the vacuum line off the fuel regulator at idle the fuel pressure goes up to 30psi is that normal or is the fuel regulator bad ? Or should I be looking at the fuel pump maybe dirty tank clogged pump filter maybe. In line filter is new

 

If your motor runs about 16 to 18 in hg vacuum, than yes your FPR seems to be fine. It's adding about 8 psi at 0 vacuum.

Seems you might have low pressure caused by fuel filter, maybe screens, maybe pump, maybe low voltage to pump.

Is motor running bad?

I ask because if your alternator or battery is going south your system voltage is low. At high rpms voltage could be higher allowing pump to push a little higher pressure. As you stated wot pressures were higher than idle with no vacuum.

Check your charging system.

 

Sorry, that's the only picture I had of it while it was out of my truck. Just like anything between the engine and the firewall it definitely isn't easy to get to. Sounds like the issue may not be with your FPR anyway. Hopefully it's something easy that rock2610d mentioned, like your filter or just low voltage. I would much rather do a filter or even alternator than a fuel pump or try to get the FPR out.